Power-transmission device



June 12, 1923.

J. C. PRATT POWER TRANSMISSION DEVICE Filed April .9, 1921 INVENToR.-

. Jo'shwa Pra,

M/[TNESSES:

A TTORNEY.

Patented lune 12, 1923.

JOSHUA C. PRATT, F FRAMINGHAM, MASSACHUSETTS.

POWER-TRANSMISSION DEVICE.

Application led April 9.

I To all 'whom t may concern:

Be it known that L'JosuUAC. Pnirrnn citizen of the United States,residing 1n Framingham, in the county of Middlesex and State ofMassachusetts, have inventedA certain new and useful Vimprovements inPower-Transmission Devices,` whereof the following is a specification,reference being had to the accompanying drawings.

My invention relates generally to transmission devices, and moreparticularly to those of the type ordinarily known as Hydraulictransmissions or clutches, whereby, under control of the ow of suitableliquid in a closed circuit or circuits, power may be ransmitted, atvariabley speeds, from a driving element to a driven element.

The primary object of my invention is to secure higher eiliciency, andgreater simplicity, both as to construction and operation thanattainable with devices heretofore designed for a similar purpose.

Other objects and attendant advantages of my invention will becomeapparent from the detailed description which follows:

' ln the drawings, Fig. l is an illustration in elevation of a powertransmission device conveniently embodying my invention, the cover plateof the casing or housing thereof having been removed so as to expose toview the mechanism upon the interior; and

Fig. 1l is an axial sectional view taken through the structure on theline H-H of the preceding` figure.

As herein shown, the mechanism of the transmission device is housedwithin a casing having the form of a drum comprehensively designated bythe numeral 1, said casing comprising a main cylindrical section ormember 2 and a circular cover disk or plate 3, which are l'relativelysecured by means of screw bolts such as shown at M in Fig. Il. The maincasing member 2 has an axial projection or boss 5 whereby it may beattached, for example, to the crank shaft of an automobile motor toserve in the capacity of a flywheel therefor. The' cover plate 3 isformed with a hollow, frustoconical protuberance 6 in turn having anintegral axial boss 7 functional as a journal or bearing for atransmission shaft 8. Within the conflnespof the casing, the shaft 8 hasformed in it, a crank 9, and its inner end, as best seen in Fig. II, issustained for rotation in an axial bore of the boss5 of the casingmember 2'. The pin 10 of the crank 9 is 1921. Serial No. 460,056.

common to a series of connecting rods 11, whose outer ends are pivotallycoordinated with the plunger pistons 12-12 of cylinders 15E-13. Saidcylinders, ofwhich there are four in number, extend radially inward fromthe peripheral wall of the casing member 2, and, in practice, are eitherintegrally formed with said casing member, or rigidly secured thereto inany approved manner. Adjacent their inner or base ends, the cylinders153-13 communicate with the interior of the casing through lateral ports15 adapted to be controlled by sleeves 16 slidably mounted about saidcylinders. Said sleeves are axially shiftable under actuation of acollar 17 slidable on the external portion ofv the journal boss 7 'ofthe casing cover member 3, said collar being connected by means ofextension rods 18 reaching to the interior of the casing, to bell cranklevers 19 which are fulcrumed about fixed pivots 20 within theprotuberance 6 of the cover member, and in turn pivotally connectedthrough radially disposed links 21 with the aforesaid sleeves.

ln practice, the casing is filled with a suitable liquid, preferablylubricatingoihwhich, under the pumping action of the plunger pistons12-12, is drawn into, and expelled *through the ports 415 of thecylinders, the

extent of port opening controlled by the shifting mechanism for thesleeves 16 determining the rate of How, and in turn the extent of freereciprocation of the pistons, thus allowingr a certain amount ofslippage between the casing 1, as a whole, and the driven transmissionshaft 8 which carries the load with the result that the latter may becaused to rotate at different speeds.

The operation of the device may be briedy described as follows:

`With the assumption that the ports 15 are fully open, as shown in theillustration, it will be apparent that as the casing 1 revolves bodilyand the lattached cylinders 13-18 with it, the pistons 124-12 are freeto reciprocate idly under the reaction of the yload which tends to holdthe transmission shaft 8 from revolving, the liquid being, as a result,continuously drawn into and expelled from the cylinders through saidports. However, as the ports are partly cl'osed by simultaneouslyshifting the control sleeves 16, the surging of the liquid as abovenoted, is correspondinglyrestricted and the free movement of the plungerpistons Iproprtionately retarded. K Under these conditions, thetransmission shaft is drivenvin the same direction as the casing 1, butat a slower speed depending upon the amount of slippage allowed betweenthe driving and the driven element under the restricted flow of theliquid in the closed system As the sleeves are gradually moved to closethe ports entirely, under similar reasoning, it will at once be seenthat the speed Vof the driven shaft increases" and graduallyapproaches'that of the casing 1, yand under complete closure of theports, the transmission shaft will obviously be -obliged to revolve inabsolute synchronism withthe casing 1 owing to the incompressibility ofthe liquid which will then l be trapped in the several cylinders `of thesystem.

From the foregoing, it will be apparent that any desired speed of thedriven transmission shaft, limited only by that of the maximum speed ofthe casing 1, may be had by proper control of the sleeve actuat- .ingmechanism.V

v Having thus described my invention, I claim:

1. AA hydraulic, power transmission device comprising a rot-ary casing,a plurality of cylinders xed to the inner periphery of the casingand-extending radially in an inward direction, each cylinder having aseries of. apertures formed adjacent its outer end, a sleeve embracingeach cylinder and slidable. longitudinally to vary .the aperture of saidopenings, a. concentric shaft having af crank portion, pistons slidablein the cylinders. with piston rod connections to thecrank portion, andmeans for simultaneously shifting the sleeves.

2. A hydraulic, power transmission device comprising a casing, aplurality of in wardly directed cylinders carried thereby and Yhavingopenings, a sleeve embracing each cylinderl and. slidable longitudinallyto vary the apertureof the opening, a cy- 'fvice comprising a drivingmember in the form of a closed, revolving, liquid filled drum casing; aseries of relatively fixed cylinders extending radially inward from theperipheral wall of the drum casing, said cylinders having formed inthem, vadjacent their base ends, a series of ports for communicationwith the interior of the casing; plunger pistons reciprocatory withinthe cylinders; a transmission shaft extending axially to the interiorvof the casing,` and having a crank formed therein; connecting rodswhereby the plunger pistons are coordinated with the crank of saidshaft; sleeves slidably mounted about the cylinders for controlling theflow of the fluid Ithrough the aforesaid ports to check,V

to variable degrees, the free reciprocation allowed the plunger pistons;and mechanism for simultaneously shifting said sleeves including acollar slidable upon an external axial, boss of the casing, said collarhaving rods vextending toY the interior of said casing; radiallydisposed links pivoted at one end to the s eeves; and/bell crank leversinterposed between the ends of the links` and the rods of the aforesaidcollar.

In testimony whereof, I have hereunto signed my namef at Framingham,Massa'- chusetts, this fifth day of April, 1921.

JOSHUA C. PRATT.

Witnesses:

RAYMOND J. CALLAHAN, CHARLES T. LEMOINE.

